Well, as someone did post, United has a policy against taking pictures with nonconsent of other passengers of their photo being taken. Additionally, there is a security issue with people taking pictures of say the cockpit door, or taking pictures when the door is open and pilots are entering/exiting, stuff like that.

Now, that said, the FA's could have been more polite about asking you based on your story, which of course is one side of the story. Since it seems to be written United policy, then they were right in asking you to delete the photos and not take them. I know I would be irked if someone took my photo in a plane without permission.

AD